Napolitano Marco, Terzaroli Niccolò, Kashyap Subash, Russi Luigi, Jones-Evans Elen, Albertini Emidio
Bayer, Kaiser-Wilhelm-Allee 1, 51373 Leverkusen, Germany.
Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Borgo XX Giugno 74, 06121 Perugia, Italy.
Plants (Basel). 2020 Feb 21;9(2):282. doi: 10.3390/plants9020282.
Heterosis is the superiority of an F hybrid over its parents. Since this phenomenon is still unclear in melon, a half diallel experiment based on eight genetically distant breeding lines was conducted in six environments of Central Italy, assessing commercially important traits: yield, total soluble solids (TSS), and days to ripening (DTR). To estimate the additive (general combining ability; GCA) and the non-additive gene effects (specific combining ability; SCA), yield was analyzed by Griffing's methods two and four, and the results were compared to the GGE (Genotype plus Genotype by Environment interaction) biplot methodology; TSS and earliness were evaluated only by Griffing's method four. Overall, GCAs were significantly more relevant than SCAs for all examined traits. Least square means (LsM), mid-parent heterosis (MPH), best-parent heterosis (BPH), as well as Euclidean and Mahalanobis' distances were calculated and compared with the genetic distance (GD). As a few correlations were found statistically significant (only for TSS), it was difficult to predict the value of a hybrid combination only by knowing the genetic distance of its parents. Despite this, heterosis was observed, indicating either the presence of epistatic effects (additive × additive interactions) and/or an underestimate of SCAs embedded within Griffing's method. The significant Env × Entries source of variation suggests development of hybrids in specific environments. The results are discussed with a breeding perspective.
杂种优势是指F1杂种相对于其亲本的优越性。由于甜瓜中这种现象仍不清楚，因此在意大利中部的六个环境中，基于八个遗传距离较远的育种系进行了半双列杂交试验，评估了商业上重要的性状：产量、总可溶性固形物（TSS）和成熟天数（DTR）。为了估计加性效应（一般配合力；GCA）和非加性基因效应（特殊配合力；SCA），采用格里芬方法二和方法四对产量进行了分析，并将结果与GGE（基因型加基因型与环境互作）双标图方法进行了比较；TSS和早熟性仅通过格里芬方法四进行评估。总体而言，对于所有检测性状，GCA比SCA的相关性显著更高。计算了最小二乘均值（LsM）、中亲杂种优势（MPH）、最好亲本品系杂种优势（BPH）以及欧氏距离和马氏距离，并与遗传距离（GD）进行了比较。由于发现一些相关性具有统计学意义（仅针对TSS），仅通过了解其亲本的遗传距离很难预测杂种组合的值。尽管如此，仍观察到了杂种优势，这表明存在上位性效应（加性×加性互作）和/或格里芬方法中嵌入的SCA被低估。显著的环境×条目变异来源表明在特定环境中培育杂种。从育种角度对结果进行了讨论。
