Golden 2-like transcription factor contributes to the major QTL against rice black-streaked dwarf virus disease

Gene pyramiding of ZmGLK36 and ZmGDIα-hel for rough dwarf disease resistance in maize

Maize rough dwarf disease (MRDD) caused by pathogenic viruses in the genus Fijivirus in the family Reoviridae is one of the most destructive diseases in maize. The pyramiding of effective resistance genes into maize varieties is a potential approach to reduce the damage resulting from the disease. Two major quantitative trait loci (QTLs) (qMrdd2 and qMrdd8) have been previously identified. The resistance genes ZmGLK36 and ZmGDIα-hel have also been cloned with the functional markers Indel-26 and IDP25K, respectively. In this study, ZmGLK36 and ZmGDIα-hel were introgressed to improve MRDD resistance of maize lines (Zheng58, Chang7-2, B73, Mo17, and their derived hybrids Zhengdan958 and B73 × Mo17) via marker-assisted selection (MAS). The converted lines and their derived hybrids, carrying one or two genes, were evaluated for MRDD resistance using artificial inoculation methods. The double-gene pyramiding lines and their derived hybrids exhibited increased resistance to MRDD compared to the monogenic lines and the respective hybrids. The genetic backgrounds of the converted lines were highly similar (90.85-98.58%) to the recurrent parents. In addition, agronomic trait evaluation demonstrated that pyramiding lines with one or two genes and their derived hybrids were not significantly different from the recurrent parents and their hybrids under nonpathogenic stress, including period traits (tasseling, pollen shedding, and silking), yield traits (ear length, grain weight per ear and 100-kernel weight) and quality traits (protein and starch content). There were differences in plant architecture traits between the improved lines and their hybrids. This study illustrated the successful development of gene pyramiding for improving MRDD resistance by advancing the breeding process.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11032-024-01466-9.

Yield components affected by rice black-streaked dwarf virus disease in rice cultivars with different resistance levels

Introduction

Rice black-streaked dwarf virus disease (RBSDVD) is one of the most destructive rice viral diseases, leading to severe yield losses in rice production. However, little is known about the yield-related components associated with the disease and no resistance cultivars have been successfully used in rice breeding.

Methods

Seven rice cultivars were analyzed in this study, including six commercial rice varieties and a new line Zhongjian No. 201 (ZJ201) containing the resistance gene OsAP47. Resistance levels of these cultivars were evaluated by artificial inoculation and yield components were collected, including panicle length (PL), spikelets per panicle (SPP), ripened grains per panicle (RGPP), as well as panicles per square meter (PPSM) and 1000-grain weight (TGW). Seed setting rate (SSR) were calculated with the data of SPP and RGPP.

Results and discussion

The results showed that ZJ201 displayed the highest resistance level and most of the commercial rice cultivars exhibited susceptible to RBSDVD. Yields of all the rice cultivars were significantly declined except ZJ201 and yield losses produced by RBSDVD were mainly due to the reduction of PL, SPP, RGPP, and TGW, suggesting that developments of these traits are associated with RBSDV infection. Resistant rice cultivar could reduce yield losses by maintaining normal development of these traits. Significant correlations were identified between resistance levels and the yield components except SSR and PPSM. The results provided useful clues for understanding the mechanisms of RBSDV invasion and its effect on rice production. ZJ201 was demonstrated as a resistance material that could be used in rice breeding.

A transcription factor ZmGLK36 confers broad resistance to maize rough dwarf disease in cereal crops

Maize rough dwarf disease (MRDD), caused by maize rough dwarf virus (MRDV) or rice black-streaked dwarf virus (RBSDV), seriously threatens worldwide production of all major cereal crops, including maize, rice, wheat and barley. Here we report fine mapping and cloning of a previously reported major quantitative trait locus (QTL) (qMrdd2) for RBSDV resistance in maize. Subsequently, we show that qMrdd2 encodes a G2-like transcription factor named ZmGLK36 that promotes resistance to RBSDV by enhancing jasmonic acid (JA) biosynthesis and JA-mediated defence response. We identify a 26-bp indel located in the 5' UTR of ZmGLK36 that contributes to differential expression and resistance to RBSDV in maize inbred lines. Moreover, we show that ZmDBF2, an AP2/EREBP family transcription factor, directly binds to the 26-bp indel and represses ZmGLK36 expression. We further demonstrate that ZmGLK36 plays a conserved role in conferring resistance to RBSDV in rice and wheat using transgenic or marker-assisted breeding approaches. Our results provide insights into the molecular mechanisms of RBSDV resistance and effective strategies to breed RBSDV-resistant cereal crops.