Paper Details

PJB-2022-225

Investigation of Potato Pre-Grafting to Induce Interspecific Crosses and Beneficial Trait Combinations

Lipan Qi
Abstract

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Abstract: 【Objective】 The development of high-yielding starch-dense tetraploid (2n = 4x = 48) potatoes derived from novel inter-ploidy crosses between high-yielding tetraploids and starch-dense wild diploids (2n = 2x = 24).【Methods】Pre-grafting of a cultivated tetraploid variety (scion) onto the wild diploid rootstock created a pre-grafted parent (PGP). Pollen from the wild diploid (WD) material was collected to fertilize the PGP. In addition to starch content and total harvested starch yield, five agronomic and quality traits (plant height, branch number, tuber number per plant, tuber weight per plant, tuber yield) were measured. Cluster and correlation analyses were performed to evaluate the starch concentration of offspring derived from the interspecific crosses. 【Results】 (1) Mean values for progeny phenotypic, agronomic and economic traits fell between the values for cultivated and wild progenitors. The highest value for starch yield appeared in F1 progeny and was 47.32% and 80.94% higher than that of both the female and male progenitors. (2) A total of 67 progenitors and progenies were distributed into three classes: ZJ1823-1 and ZJ1882-2, grouped into a super-parent heterosis class with high starch concentrations. ZJ1837.1 and another 39 progeny had medium-starch concentrations, similar to the female progenitor ZJ1814.1, and an additional 26 materials had low starch concentrations, which was the same for 91% of the male diploids. (3) Progeny ploidy was identified by flow cytometry. Among the 53 F1 progenies, 22 were tetraploid, 29 triploid and two diploid, accounting for 41.5%, 54.7% and 3.8%, respectively. In the high starch yield range (>7500 kg/ha), tetraploid, triploid and diploid accounted for 63.6%, 36.4% and 0%, respectively. Correlation analysis showed that ploidy is positively correlated (p. value < 0.05) with increased plant height, growth days, tuber weight per plant, tuber number and starch production, and negatively correlated with stem number. Most of the progenies of high starch density displayed greater plant height and ploidy, more extended growth duration, high tuber weight per plant and higher tuber yield. (4) Four progeny exhibited higher levels of starch yield (>9000 kg/ha; two tetraploids and two triploids) and one with super-high starch concentration (≥25%; tetraploid), which attained this project’s breeding objective of introducing high starch contents from diploid progenitors to F1 tetraploid progeny in one breeding cycle. 【Conclusion】 Using the cultivated tetraploid potato as the female parent, high-starch wild diploid species as the male parent, and PGP as a bridge to bypass interspecific incompatibility, sexual hybridization achieved via grafting fusion can be used to create new potato progeny with desirable traits, such as high starch, derived from materials of different ploidy.

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