Selection of Standard Rice Cultivars for Evaluating Cracking Resistance and Finding a Novel QTL Responsible for It

抄録

To breed rice cultivars with kernel-cracking resistance, we selected new standard cultivars for evaluation. Among 21 cultivars rated from “resistant” to “weak” in Tohoku, Hokuriku, and western Japan, we regarded “Ouu 431,” “Ukei 1210,” “Eminokizuna,” and “Yamadawara” as resistant. We selected two resistant lines, namely, “IRSL 30” and “IRSL 37,” as breeding materials from the chromosome segment substitution lines of “Itadaki” (Oryza sativa L.) × donor Oryza rufipogon and identified a major QTL, qCR8-2, responsible for cracking resistance by QTL analysis using F₄ individuals derived from “Itadaki/IRSL 30” and “Itadaki/IRSL 37.” “Chugoku PL2,” which was selected from the progeny of “Itadaki/IRSL 37,” has qCR8-2 in an “Itadaki” background. It had better palatability and a lower broken rice ratio during milling compared with “Itadaki.” In this case, improved cracking resistance led to improved palatability and milling traits.