Question

The necrohormone theory for the induction of polyembryony was proposed by………
A. Leroy
B. Haberlandt
C. Maheshwari
D. Winkler

Answer 1

Hint: Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg.
Polyembryony was first reported by Leeuwenhoek in the year 1719.

Complete answer:
Haberlandt proposed the necrohormone theory for the induction of polyembryony in the year 1991-1992.
The theory states that degenerating cells of the nucleus acts as a source of stimulus for the adjacent cell to divide and form adventives embryos.
The theory could not be validated as adventives embryo could not be induced by damaging the nucellar cells.
But the genetic theory is the most accepted theory as the presence of polyembryony is determined by genes.

So, the answer is B. Haberlandt

Additional information:
-Polyembryony can occur in humans which can result in identical twins, though the process is random and at a low frequency.
-Polyembryony occurs regularly in many species of vertebrates, invertebrates, and plants.
-Around 20 genera of gymnosperms undergo polyembryony known as "cleavage polyembryony," where the original zygote splits into many identical embryos.
-In some plant taxa, the many embryos of polyembryony eventually give rise to only a single offspring.
-The mechanism underlying the phenomenon of single offspring is described in Pinus sylvestris to be programmed cell death (PCD), which removes all but one embryo.
-The genus Citrus has a number of species that undergo polyembryony, where multiple nucellar-cell-derived embryos exist alongside sexually-derived embryos.

Note:
Polyembryony plays an important role in horticulture, cytogenetics and plant breeding.
Nucellar embryony helps in producing genetically uniform seedlings of the parental type for better clones of scion and rootstock.
Polyembryony helps in large scale propagation of desired genotypes.