Search Results (3)

Increasing grain yield is required to meet the rapidly expanding demands for food, feed, and fuel. Inflorescence meristems are central to plant growth and development. However, the question concerning whether inflorescence development can be regulated to improve grain yield remains unclear. Here, we describe a naturally occurring single recessive mutation called fea5 that can increase grain yield in maize. Using bulk segregant analysis sequencing (BSA-seq), the candidate region was initially mapped to a large region on chromosome 4 (4.68 Mb–11.26 Mb). Transcriptome sequencing (RNA-seq) revealed a total of 1246 differentially expressed genes (DEGs), of which 835 were up-regulated and 411 were down-regulated. Further analysis revealed the enrichment of DEGs in phytohormone signal transduction. Consistently, phytohormone profiling indicated that auxin (IAA), jasmonic acid (JA), ethylene (ETH), and cytokinin (CK) levels increased significantly, whereas the gibberellin (GA) level decreased significantly in fea5. By integrating BSA-seq with RNA-seq, we identified Zm00001d048841 as the most likely candidate gene. Our results provide valuable insight into this new germplasm resource and the molecular mechanism underlying fasciated ears that produce a higher kernel row number in maize. Full article

Meristems are central to plant growth and development, yet evidence of directly manipulating this control to improve crop yield is scarce. Kernel row number (KRN) is an important agronomic trait that can directly affect maize (Zea mays L.) yield. However, this trait is difficult to select by phenotyping, since it is highly variable in the mixed genetic backgrounds in early selfing generations. This study sought to improve this trait by marker-assisted backcrossing (MABC) of a weak allele of FASCIATED EAR 2 that is known to affect inflorescence meristem size, but the effect of which on yield is unclear. All of the four introgressed tropical elite inbreds of different heterotic groups, which are homozygous for the fea2-1328 allele, had 2–5 more KRNs compared to their respective recurrent parents. Furthermore, one hybrid made from crosses between two introgressed parents also had KRN increases that resulted in up to 28% yield increase compared to the original hybrid across multiple yield trials. The novel negative effects of the pericentromeric fea2 and/or its linkage drag effect on plant height, seed weight, and ear length, which could prevent line improvement, were revealed in several genetic backgrounds. Integration of conventional phenotypic selection to overcome these undesirable effects was discussed. This is the first work to demonstrate the possibility to increase yield of maize varieties using a mutation in a meristem size regulator. The crossing, selection strategies, and recombinant lines in this work can be applied to other elite maize hybrids and provide a potentially straightforward, non-transgenic way to improve the yield of an existing variety by 8–28%. Full article

Induced point mutations are important genetic resources for their ability to create hypo- and hypermorphic alleles that are useful for understanding gene functions and breeding. However, such mutant populations have only been developed for a few temperate maize varieties, mainly B73 and W22, yet no tropical maize inbred lines have been mutagenized and made available to the public to date. We developed a novel Ethyl Methanesulfonate (EMS) induced mutation resource in maize comprising 2050 independent M2 mutant families in the elite tropical maize inbred ML10. By phenotypic screening, we showed that this population is of comparable quality with other mutagenized populations in maize. To illustrate the usefulness of this population for gene discovery, we performed rapid mapping-by-sequencing to clone a fasciated-ear mutant and identify a causal promoter deletion in ZmCLE7 (CLE7). Our mapping procedure does not require crossing to an unrelated parent, thus is suitable for mapping subtle traits and ones affected by heterosis. This first EMS population in tropical maize is expected to be very useful for the maize research community. Also, the EMS mutagenesis and rapid mapping-by-sequencing pipeline described here illustrate the power of performing forward genetics in diverse maize germplasms of choice, which can lead to novel gene discovery due to divergent genetic backgrounds. Full article