First of all let’s summarize some 2012 highlights one last time:
Interspecific BC1 Jatropha hybrid
In December we have reached the BC2 stage following our interspecific breeding path. The first batch of BC2s are all descendants of an early and white flowering BC1, the female parent of which is in turn our non-toxic, male-sterile Jatropha plant from the wild in Guatemala. The pollen donor was an interspecific hybrid crossed from an elite toxic JcL cultivar and Jatropha integerrima. Many more genetically diverse BC2 hybrids will follow over the course of this year as our large population of different BC1s gradually start flowering. Some actually have done so by now.
Quite unexpectedly earlier in 2012 we observed enormous heterosis effects (hybrid vigor) in several different intraspecific hybrids we had kind of neglected. Some increasing seed weight compared to their parents by up to 100%. A finding which made us gravely rethink and adjust our breeding processes and objectives. Later we then saw heterosis again in another hybrid with fruit clusters consistently around 50 fruits and seed weight still significantly above the parental average. All three of those hybrids initiated flowering only 6 months after seed germination. These plants actually convinced us that consistent seed yields of 10 kg and more are within reach. We do expect to see a lot more of positive heterosis results as we only started to fully exploit our germplasm collection by crossing our genetically most distant accessions in the late months of 2012.
Two more areas are worth mentioning where we expanded our knowledge of Jatropha development significantly during 2012, possibly taking us to a global leadership position in Jatropha R&D: Grafting and multi species (more than 2) Jatropha hybridization. We have made great progress on both work streams and do expect major break-throughs to be reported by the end of this year.
Unusual Jatropha flowers on a hybrid BC1
The walk through of our 2012 results actually already covers most of the outlook for 2013:our interspecific hybrids will most likely reach BC4 stage moving closer to possible commercial exploitation through selection from a widening population and dedicated heterosis breeding will teach us all we need to know to develop a first line of F1 hybrids in 2014 from our germplasm range.
The first 6 weeks of 2013 gave us an extra boost in confidence looking at the great developments we saw in the usually not very eventful core dry season here in Ghana. This is symbolized by the beautiful flowers on the left, another BC1 which set flowers for the first time in January which were manually pollinated and emerged into 4 fast growing fruits by now.
We have harvested a first batch of Jatropha seeds from the intraspecific hybrid exhibiting by far the strongest heterosis effects in leave size and height. And we were up for a real surprise.
We had recently seen 2 scientific reports on heterosis trials with Jatropha in South East Asia describing maximum positive heterosis in seed weight of up to 25%. We therefore never expected to see our highest 100-seed weight increasing so much. Extrapolated from 20 harvested seeds it slightly exceeds 110g. Size can be compared well in the picture above with control being a typical average size seed at a 100-seed weight of 56g.
Our own findings are completely in line with the above mentioned reports, while showing even further potential. We still have to cross those parental lines in our possession with the greatest distance according to our genetic map. As all available results point to the very strong positive correlation between heterozygosity and heterosis in intraspecific Jatropha hybrids we expect that our latest findings can easily be exceeded once all our planned hybrid crosses have fruited.
This latest success supports our ongoing planning for a dedicated heterosis breeding sub-program which could allow for stable, highly superior F1 hybrids within less than 2 years.
In the second half of August we successfully germinated the first three F2 generation seedlings from one of our interspecific hybrids. From now on we have fast growing F2 Jatropha interspecific hybrids for further breeding. While some research reports indicate that this type of interspecific hybrid is sterile or not interesting for breeding, we observe ongoing successful seed development on several of our early F1 plants deriving from different Jatropha curcas female parents. So we expect more additions to this F2 generation population in the near future.
As expected from applying simple Mendelian rules the F2 generation phenotypically exhibits much more diversity than the F1 generation.
All of the 3 seedlings we have so far appear strong and healthy. However, only the one on the left hand side seems to be as fast developing as expected while the other 2 are only moving along slowly.
F2 seedlings of interspecific JcL hybrids 1 month old showing wide variation
We expect our F2 interspecific population to grow very fast over the coming months involving many different F1 interspecific parents with genetically very different Jatropha curcas parents in turn. Currently many F1s are initiating their first flowering. On the interspecific route of our breeding program this is really what we have worked on for almost 3 years. We have clearly begun moving into terrain which has not previously discussed in the scientific literature to the best of our knowledge.
This development marks another success in achieving our initial target to bring as much variability into the germplasm available to our Jatropha breeding platform for future improvements through selection. We are now able to start work on a real ground breaking next step we had been planning for since we did the first interspecific cross almost 2 years ago. With a little luck first results will become visible before the end of the year.
Further observations on the interspecific breeding route will be published here as much as possible, but of course we will have to start protecting our intellectual property where we reach the forefront of commercial hybrid development as we are expecting a meaningful patent application before too long.
Before our proof-of-concept phase officially came to an end on June 30th, 2012 we succeeded in taking our efforts to the next level. Our first Jatropha hybrid backcrosses have germinated and reached seedling stage by mid June. This achievement marks an enormously important step forward for the Bionic Palm Jatropha breeding program.
The above picture shows the huge variability among our earliest BC1 seedlings. Over the coming months this collection will grow into the hundreds. We aim for a BC1 population incorporating all of our original parental germplasm and most of its cross combinations. Thus we will gain the maximum possible genetic variability base which we can later draw from when we breed for truly superior commercially usable hybrids.
What we define as our BC1 population is the result of back-crossing interspecific Jatropha curcas x Jatropha integerima hybrids into our parental Jatropha curcas accessions. This is a standard breeder’s approach if he wants to transfer specific traits (certain properties) from a related species into his species of interest. However, we are not into pedigree breeding at this time. Our primary aim is still to increase genetic variability of our population to the utmost possible.
We are looking for the greatest possible heterozygosity in these plants which can be assumed to be 100% in many cases. According to scientific research reports on the genetics of Jatropha this can only be achieved through an interspecific breeding route. While this kind of approach is very time consuming we do expect to gain a substantial shift in the Jatropha genetics.