AUTHOR=Tong Lixiu , Yan Mingzhu , Zhu Mang , Yang Jie , Li Yipu , Xu Mingliang 

TITLE=ZmCCT haplotype H5 improves yield, stalk-rot resistance, and drought tolerance in maize

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.984527

DOI=10.3389/fpls.2022.984527

ISSN=1664-462X

ABSTRACT=<p>The <italic>ZmCCT</italic> locus underlies both stalk-rot resistance and photoperiod sensitivity in maize (<italic>Zea mays</italic> L.). We previously introduced nine resistant <italic>ZmCCT</italic> haplotypes into seven elite but susceptible maize inbred lines (containing the haplotype <italic>H1</italic>) to generate 63 backcross families. Here, we continued backcrossing, followed by selfing, to develop 63 near-isogenic lines (NILs). We evaluated 22 of these NILs for stalk-rot resistance and flowering time under long-day conditions. Lines harboring the haplotype <italic>H5</italic> outperformed the others, steadily reducing disease severity, while showing less photoperiod sensitivity. To demonstrate the value of haplotype <italic>H5</italic> for maize production, we selected two pairs of NILs, 83B28<italic><sup>H1</sup></italic>/83B28<italic><sup>H5</sup></italic> and A5302<italic><sup>H1</sup></italic>/A5302<italic><sup>H5</sup></italic>, and generated F<sub>1</sub> hybrids with the same genetic backgrounds but different <italic>ZmCCT</italic> alleles: 83B28<italic><sup>H1</sup></italic> × A5302<italic><sup>H1</sup></italic>, 83B28<italic><sup>H1</sup></italic> ×  A5302<italic><sup>H5</sup></italic>, 83B28<italic><sup>H5</sup></italic> × A5302<italic><sup>H1</sup></italic>, and 83B28<italic><sup>H5</sup></italic> × A5302<italic><sup>H5</sup></italic>. We performed field trials to investigate yield/yield-related traits, stalk-rot resistance, flowering time, and drought/salt tolerance in these four hybrids. 83B28<italic><sup>H5</sup></italic> × A5302<italic><sup>H1</sup></italic> performed the best, with significantly improved yield, stalk-rot resistance, and drought tolerance compared to the control (83B28<italic><sup>H1</sup></italic> × A5302<italic><sup>H1</sup></italic>). Therefore, the <italic>ZmCCT</italic> haplotype <italic>H5</italic> has great value for breeding maize varieties with high yield potential, stalk-rot resistance, and drought tolerance.</p>