Getting to the roots of Cicer arietinum L. (chickpea) to study the effect of salinity on morpho-physiological, biochemical and molecular traits

Morpho-physiological studies of sandalwood-host interaction under individual and interactive water and salt stress

To find out the possibilities of growing white sandalwood in sub-tropical regions of India where farmers facing the problem of water deficit and salinity stress, a RBD experiment was conducted. Sandalwood grown alone and with five selected hosts (Alternanthera sp., Neem, Shisham, Dek and Agarwood) on the basis of prior study under water deficit, salinity stress and combined water deficit and salinity stress. Sandalwood plants were harvested after 180 days of imposing stress treatments. Morphological traits (plant height, collar diameter, shoot fresh and dry biomass) showed significant reduction under water deficit and salinity stress, which were further aggravated under combined water deficit and salinity stress. Studied plant water traits, ionic balance and gas exchange attributes were also reduced by these stresses. While among studied host, Shisham and Dek identified as the best host species under water deficit, salinity and interactive stress by maintaining ion homeostasis, osmotic adjustments and plant water regulation. Results depicted that sandalwood plants cultivated alone were not able to survive under salinity and combined stress conditions and showed poor growth under water deficit and control conditions. Different indices were also calculated based on morpho-physiological and ionic traits and also indicated that sandalwood grown with Dalbergia sissoo and Melia dubia showed higher drought, salt and stress tolerance potential, which made sandalwood adaptable under these stresses. Therefore, the present study signifies the importance of host especially D. sissoo and M. dubia which might be excellent long-term host species for sandalwood cultivation under sub-tropical conditions to thrive under changing environments.

Advancing Chickpea Breeding: Omics Insights for Targeted Abiotic Stress Mitigation and Genetic Enhancement

Chickpea is a major source of proteins and is considered the most economically vital food legume. Chickpea production is threatened by several abiotic and biotic factors worldwide. The main constraints limiting worldwide chickpea production are abiotic conditions such as drought, heat, salinity, and cold. It is clear that chickpea is treasured for its nutritive value, in particular its high protein content, and hence study of problems like drought, cold and salinity stresses are very important concerning chickpeas. In this regard, several physiological, biochemical, and molecular mechanisms are reviewed to confer tolerance to abiotic stress. The most crippling economic losses in agriculture occur due to these abiotic stressors, which affect plants in many ways. All these abiotic stresses affect the water relations of the plant, both at the cellular level as well as the whole-plant level, causing both specific and non-specific reactions, damage and adaptation reactions. These stresses share common features. Breeding programs use a huge collection of over 100,000 chickpea accessions as their foundation. Significant advancements in conventional breeding, including mutagenesis, gene/allele introgression, and germplasm introduction, have been made through this method. Abiotic tolerance and yield component selection are made easier by creating unique DNA markers for the genus Cicer, which has been made possible by developments in high-throughput sequencing and molecular biology. Transcriptomics, proteomics, and metabolomics have also made it possible to identify particular genes, proteins, and metabolites linked to chickpea tolerance to abiotic stress. Chickpea abiotic stress tolerance has been directly and potentially improved by biotechnological applications, which are covered by all 'Omics' approaches. It requires information on the abiotic stress response at the different molecular levels, which comprises gene expression analysis for metabolites or proteins and its impact on phenotype. Studies on chickpea genome-wide expression profiling have been conducted to determine important candidate genes and their regulatory networks for abiotic stress response. This study aimed to offer a detailed overview of the diverse 'Omics' approaches for resilience's to abiotic stresses on chickpea plants.

Haplotypes of ATP-Binding Cassette CaABCC6 in Chickpea from Kazakhstan Are Associated with Salinity Tolerance and Leaf Necrosis via Oxidative Stress

Salinity tolerance was studied in chickpea accessions from a germplasm collection and in cultivars from Kazakhstan. After NaCl treatment, significant differences were found between genotypes, which could be arranged into three groups. Those that performed poorest were found in group 1, comprising five ICC accessions with the lowest chlorophyll content, the highest leaf necrosis (LN), Na+ accumulation, malondialdehyde (MDA) content, and a low glutathione ratio GSH/GSSG. Two cultivars, Privo-1 and Tassay, representing group 2, were moderate in these traits, while the best performance was for group 3, containing two other cultivars, Krasnokutsky-123 and Looch, which were found to have mostly green plants and an exact opposite pattern of traits. Marker-trait association (MTA) between 6K DArT markers and four traits (LN, Na+, MDA, and GSH/GSSG) revealed the presence of four possible candidate genes in the chickpea genome that may be associated with the three groups. One gene, ATP-binding cassette, CaABCC6, was selected, and three haplotypes, A, D1, and D2, were identified in plants from the three groups. Two of the most salt-tolerant cultivars from group 3 were found to have haplotype D2 with a novel identified SNP. RT-qPCR analysis confirmed that this gene was strongly expressed after NaCl treatment in the parental- and breeding-line plants of haplotype D2. Mass spectrometry of seed proteins showed a higher accumulation of glutathione reductase and S-transferase, but not peroxidase, in the D2 haplotype. In conclusion, the CaABCC6 gene was hypothesized to be associated with a better response to oxidative stress via glutathione metabolism, while other candidate genes are likely involved in the control of chlorophyll content and Na+ accumulation.

Delineating the role of host plants in regulating the water and salinity stress induced changes in sandalwood roots

The interaction of root hemi-parasite (sandalwood) with its hosts is crucial for establishing successful plantations under abiotic stresses. In the present study, we explored the best possible host for sandalwood along with its effect on sandalwood physiology in terms of water and nutrients. Interactive effects of host species (Alternanthera sp., Azadirachta indica, Dalbergia sissoo, Melia dubia, and Aquilaria malaccensis) with sandalwood were observed under eight treatments {100% best available water (BAW); 100% BAW + nutrient medium; 50% water deficit; 50% water deficit + nutrient medium; 100% saline water (ECiw 8ds/m); 100% saline water (ECiw 8ds/m) + nutrient medium; 50% water deficit + saline water (ECiw 8ds/m); and 50% water deficit + saline water (ECiw 8ds/m) + nutrient medium}. A significant change in morpho-physiological traits of sandalwood roots was observed under different stress conditions, which were slightly improved through external supply of nutrient medium. Dalbergia sissoo (Shisham) and Melia dubia (Dek) seemed to be the best host plants providing better environment for sandalwood growth and development, i.e., higher plant height (59.7 and 53.68 cm) and collar diameter (3.24 and 3.07 mm) under stresses by maintaining water and ionic balance. Root length is an important parameter that was reduced by 27.58%, 19.22%, and 36.3% under water deficit, salinity, and combined stress of water deficit and salinity. Sandalwood grown with D. sissoo and M. dubia maintained the lowest Ψw (- 1.38 MPa) and Ψs (- 1.47 and - 1.48 MPa), respectively. In addition, sandalwood cultivated with D. sissoo and A. indica had higher accumulation of soluble proteins (0.48 and 0.42 mg/g) and soluble sugars (98.56 and 91.04 mg/g) in their roots. Results also showed that sandalwood roots had higher K+/Na+ with compatible host, i.e., with A. indica (1.85) and D. sissoo (1.83) than other studied hosts. It was also observed that sandalwood plants could not grow and survive alone under stress conditions even with application of nutrient medium. Based on the morphological traits, it was observed that sandalwood grown with hosts, Dalbergia sissoo and Melia dubia, was able to tolerate stress conditions better than other studied hosts. We can further recommend growing sandalwood with D. sissoo and M. dubia as a viable option to endure adverse environmental conditions.

Host Plant Modulated Physio-Biochemical Process Enhances Adaptive Response of Sandalwood (Santalum album L.) under Salinity Stress

Salinity is one of the most significant abiotic stress that affects the growth and development of high-value tree species, including sandalwood, which can also be managed effectively on saline soils with the help of suitable host species. Therefore, the current investigation was conducted to understand the physiological processes and antioxidant mechanisms in sandalwood along the different salinity gradients to explore the host species that could support sandalwood growth in salt-affected agro-ecosystems. Sandalwood seedlings were grown with ten diverse host species with saline water irrigation gradients (ECiw~3, 6, and 9 dS m-1) and control (ECiw~0.82 dS m-1). Experimental findings indicate a decline in the chlorophyll content (13-33%), relative water content (3-23%), photosynthetic (27-61%) and transpiration rate (23-66%), water and osmotic potential (up to 137%), and ion dynamics (up to 61%) with increasing salinity levels. Conversely, the carotenoid content (23-43%), antioxidant activity (up to 285%), and membrane injury (82-205%) were enhanced with increasing salinity stress. Specifically, among the hosts, Dalbergia sissoo and Melia dubia showed a minimum reduction in chlorophyll content, relative water content, and plant water relation and gas exchange parameters of sandalwood plants. Surprisingly, most of the host tree species maintained K+/Na+ of sandalwood up to moderate water salinity of ECiw~6 dS m-1; however, a further increase in water salinity decreased the K+/Na+ ratio of sandalwood by many-fold. Salinity stress also enhanced the antioxidative enzyme activity, although the maximum increase was noted with host plants M. dubia, followed by D. sissoo and Azadirachta indica. Overall, the investigation concluded that sandalwood with the host D. sissoo can be successfully grown in nurseries using saline irrigation water and, with the host M. dubia, it can be grown using good quality irrigation water.

Network interactions with functional roles and evolutionary relationships for BURP domain-containing proteins in chickpea and model species

The functional significance and evolutionary relationships of BURP domain-containing genes unique to plants is of interest. Network analysis reveals different associations of BURP proteins with other proteins and functional terms, throwing light on their involvement in various biological processes and pathways. The gene expression data reveals that BURP genes are affected by salinity stress, reflecting diverse expression patterns in roots and shoots.