US-12622406-B2 - Methods for the production of seed with improved seed germination properties

Abstract

The present invention provides methods for the production of plant inbred seed, or for the production of plant hybrid seed, wherein the seed obtained exhibits altered and/or improved germination properties, in particular improved germination properties such as enhanced seed germination rate, enhanced seed germination capacity and/or enhanced seedling fresh weight. The present invention also provides for the use of periclinal chimera plants for improving germination properties of seed.

Inventors

• Jeroen Stuurman

Assignees

• KEYGENE N.V.

Dates

Publication Date

20260512

Application Date

20220211

Priority Date

20161223

Claims (7)

1. 1 . A seed comprising an embryo with a genotype identical to a genotype obtained by a cross of plant A and plant B, and an integument having the genotype of plant C, wherein the genotypes of plants A and C differ from each other, wherein plant C is a hybrid, wherein the seed has at least one improved germination property as compared to the seed obtained by crossing plant A with plant B, wherein the improved germination property is selected from the group consisting of germination capacity, uniformity of germination, germination rate, and seedling fresh weight, wherein the plant A, the plant B, and the plant C are from Solanum lycopersicum, Solanum pennellii, Solanum habrochaites, Solanum pimpinellifolium , or hybrids thereof, and wherein the seed is obtained by pollinating, with pollen of plant B, a periclinal chimera plant comprising an L2-shoot meristem layer that has the genotype of the plant A, and an L1-shoot meristem layer giving rise to the integument of the seed that has the genotype of the plant C.
2. 2 . The seed of claim 1 , wherein the genotype of plant C comprises part of the genotype of plant A and/or plant B.
3. 3 . The seed of claim 1 , wherein the genotype of plant A is identical to the genotype of plant B.
4. 4 . The seed of claim 1 , wherein one or more of plants A, B, and C are hybrids of species of the same genus.
5. 5 . The seed of claim 1 , wherein plants A, B, and C are plants of the same species.
6. 6 . A pollinated periclinal chimera plant that produces the seed of claim 1 .
7. 7 . The pollinated periclinal chimera plant of claim 6 , wherein the periclinal chimera plant is a periclinal chimera tomato plant comprising the L2-shoot meristem layer obtained from the Solanum lycopersicum plant A and an L1- and, optionally, L3-shoot meristem layer obtained from a hybrid plant C; wherein plant C is a hybrid of Solanum lycopersicum x Solanum pennellii hybrid plant, Solanum lycopersicum x Solanum habrochaites hybrid plant or Solanum lycopersicum x Solanum pimpinellifolium.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Pat. No. 11,266,115 issued from U.S. application Ser. No. 16/449,334 filed Jun. 21, 2019, which application is a continuation of International Patent Application No. PCT/EP2017/084301, filed Dec. 22, 2017, which claims priority to Netherlands Patent Application No. 2018059, filed Dec. 23, 2016. The contents of these applications are herein incorporated by reference in their entireties. FIELD OF THE INVENTION The present invention relates to the field of agriculture. In particular, the present invention relates to seed production, and to methods of improving the quality of seeds produced, in particular methods of improving seed germination properties. BACKGROUND OF THE INVENTION The standard solution to enhance crop traits has been genetics and breeding. However, classical breeding techniques can have as side effect that properties of seeds are affected. For instance for tomato, a significant proportion of new F1-hybrids do not enter the market because of inferior seed quality, i.e. inferior seed germination capacity, seed germination uniformity, seed germination rate and/or seedling fresh weight and vigour, which means a substantial loss of research investments to the plant breeding industry, and hampering of progress in breeding. It is necessary for hybrid seeds to germinate at least to 80-85% in order for it to be commercially viable after priming. It is of primary concern for a seed company not only to improve plant traits, but also to produce seed with good germination properties. For example, high fruit or leaf yield, or exaggerated/semi-natural characters such as very large fruit size in beef tomatoes, may show a negative pleiotropic effect on seed quality, which may amongst other possibilities result from unfavourable assimilate partitioning away from the developing seed, and resulting in low seed germination capacity, seed germination uniformity, seed germination rate and/or seedling fresh weight and vigour. In such case, a balance must be sought between plant output traits and seed traits, with both aspects negatively compromised. Where seed quality may in principle be improved by breeding, it will be time-consuming and difficult, and, most importantly, it may affect other desirable genomic properties. As a quantitative trait, it will require the introduction of multiple favourable loci into a desired genome. Particularly in breeding germplasm wherein seed quality has been neglected as a target of selection, the necessity to re-acquire good seed germination properties will be a major setback in the breeding programs. Thus, there is an urgent need in the art to improve properties of seeds—like seed germination capacity, seed germination uniformity, seed germination rate and/or seedling fresh weight and vigour—produced by plants, without interfering with the genetic composition of the inbred or hybrid seeds, which were developed in order to produce plants with desired agronomic or horticultural traits, and without the need to go back into the pedigrees and correct the seed quality deficits by classical breeding and selection. Solution Provided by the Present Invention The present inventor has come to the insight that a solution to the above-mentioned problems can be provided by producing seed of an existing commercial inbred line or F1-hybrid cultivar within the fruits of another cultivar making use of a periclinal chimera plant. Because this production system does not require an adaptation in the genetics of the particular cultivars used, the above-mentioned problems of the standard solution involving breeding and/or genetics are overcome. It is known that the L2-shoot meristem layer of a periclinal chimera plant determines the genotype of the gametes (e.g. Filippis et al. Using a periclinal chimera to unravel layer-specific gene expression in plants, The Plant Journal, 2013, 75: 1039-1049). Further, preliminary investigations were done to investigate the usefulness of this technology in the provision of new cultivars, for instance by making chimera of nightshade and tomato using, however, with disappointing results (Lindsay et al. Graft chimeras and somatic hybrids for new cultivars, New Zealand journal of Botany, 1995, Vol. 33: 79-92). Surprisingly, it was found that the germination properties of seed can be enhanced dramatically by altering the genotype of the L1 and/or L3-shoot meristem layer of the female parent without changing the genotype of the resulting seed. This enhancement may mean that a commercially unprofitable hybrid line may become commercially viable. During the production of sowing seed, the health and vigour of the maternal plant (i.e. the one that carries the seed as its offspring) is instrumental to obtain a good quality of seeds. This is true for all production systems, whether they are based on the production of inbred seed or F1-hybrid seed, and the invention provides a solution with a very g